The present invention relates to a resin-sealed semiconductor device, especially a semiconductor device sealed with a resin covering only one side opposite to the base. More particularly, the present invention relates to a semiconductor device characterized by its sealing resin.
The recent downsizing and miniaturization of electronic machines and equipment is accompanied by semiconductors having reduced size and thickness and improved performance. The conventional semiconductor device is composed of a semiconductor element and a lead frame which are sealed by resin such that both sides thereof are covered except for those parts by which it is mounted on a printed circuit board. Therefore, the miniaturization of semiconductor device itself needs improvement in lead frame (as the base) and sealing resin. As the result, there have been developed TSOP (thin small outline package) and QFP (quad flat package), the former having sealing resin in reduced volume and thickness, the latter having a large number of pins.
In order to reduce the mounting area and to improve the performance, there has been developed a new semiconductor device constructed such that terminals to connect the semiconductor device to the mother board are arranged on the back of the base of the semiconductor device. Unfortunately, this structure has the disadvantage that the semiconductor device is liable to warp because only one side opposite to the base is covered with the sealing resin, unlike the conventional semiconductor device which has both sides thereof covered with the sealing resin. Warping hampers the mounting on a flat mother board, causes peeling at the interface between the base and the semiconductor element, and leads to failure in the thermal cycle test and popcorn resistance test.
It is an object of the present invention to provide an epoxy resin composition and a semiconductor device sealed therewith. Said epoxy resin composition exhibits good adhesiveness, hardly warps the semiconductor device, and gives good results in the thermal cycle test and popcorn resistance test, when it is applied to the semiconductor device constructed such that only one side opposite to the base is covered with a sealing resin unlike conventional semiconductor devices.
The present inventors completed this invention as the result of their extensive studies on the semiconductor device sealed with a resin covering only one side opposite to the base, for its improvement in resin adhesion, warp reduction, and thermal cycle properties and popcorn resistance. The gist of the present invention resides in an epoxy resin composition to seal semiconductors constructed of a semiconductor element, a base to support said semiconductor element, and an epoxy resin composition covering only one side opposite to the base, said epoxy resin comprising (A) epoxy resin, (B) hardener, and (C) inorganic filler, and giving a cured product which has (a) a flexural modulus of elasticity of 10 to 30 GPa at 23xc2x0 C. and (b) a coefficient of linear expansion of 4xc3x9710xe2x88x926/K to 10xc3x9710xe2x88x926/K in the temperature range from 23xc2x0 C. to the glass transition point, with the product of (a) and (b) being smaller than 2xc3x9710xe2x88x924 GPa/K.